1. Field of the Invention
The present invention relates to a Radio Frequency (RF) transceiver apparatus in a Time Division Duplexing (TDD) wireless communication system. More particularly, the present invention relates to an apparatus and a method for protecting a Low Noise Amplifier (LNA) of a receiving stage in the TDD wireless communication system.
2. Description of the Related Art
A Time Division Duplexing (TDD) wireless communication system realizes bidirectional communications by time-dividing the same frequency and splitting one frame into transmission and reception. Accordingly, the wireless communication system switches a high-power Radio Frequency (RF) transmit signal and a low-power RF receive signal using a Transmit/Receive Antenna Switch (TRAS).
The TRAS serves to protect a Low Noise Amplifier (LNA) by shutting down the transmit power supplied to a receiving end in a transmission mode, and to reduce noise in a transmitting end in a reception mode.
FIG. 1 depicts an RF transceiver apparatus in a TDD wireless communication system according to the related art.
Referring to FIG. 1, the RF transceiver apparatus includes a TDD controller 100, a transmitter 110, a TRAS 120, a front end block 130, and a receiver 140.
The TDD controller 100 issues TDD control signals to control each block according to transmission and reception modes. For example, the TDD controller 100 issues a TDD Control signal for Transceiver (TCT) control signal to control the transmitter 110. The TDD controller 100 issues a TDD Control signal for a TRAS (TCTR) control signal to control the TRAS 120. The TDD controller 100 issues a TDD Control signal for Receiver (TCR) control signal to control the receiver 140.
In a transmission mode, the transmitter 110 converts a baseband modulated signal input from a modem (not shown) into an RF signal under the control of the TDD controller 100. The transmitter 110 power-amplifies the RF signal using a power amplifier disposed in the back end. Next, the transmitter 110 outputs the amplified RF signal to the front end block 130 via the TRAS 120.
In the transmission mode, the TRAS 120 interconnects the transmitter 110 and the receiver 140 and isolates the transmission path from the receiver 140 under the control of the TDD controller 100.
In the reception mode, the TRAS 120 interconnects the front end part 130 and the receiver 140 and isolates the reception path from the transmitter 110 under the control of the TDD controller 100.
In the reception mode, the receiver 140 low noise amplifies the low-power RF receive signal fed from the front end block 130 via the TRAS 120 under the control of the TDD controller 100.
The front end block 130 includes a Band Pass Filter (BPF). The front end block 130 filters the transmit signal fed from the TRAS 120 in the service band and outputs the filtered transmit signal to an antenna. Also, the front end block 130 filters the receive signal fed from the antenna in the service band and outputs the filtered receive signal to the TRAS 120.
The TRAS 120 can include an isolator 122, a circulator 124, a pass and reflection block 126, and an RF switch 128.
The isolator 122, in the transmission mode, absorbs the reflected signal so that the reflected signal caused by the incorrect operation of the transmission path may not be totally reflected by the pass and reflection block 126 and transferred to the transmitter 110.
The circulator 124 sends the RF transmit and receive signals to a single direction.
The pass and reflection block 126 reflects the high-power RF transmit signal and passes the low-power RF receive signal.
The RF switch 128 isolates the transmission path and the receiver 140 in the transmission mode. For example, in the transmission mode, the RF switch 128 disconnects from the receiver 140. In the reception mode, the RF switch 128 connects the reception path with the receiver 140.
As discussed above, the isolator 122, which protects the transmitter 110 by absorbing the reflected signal in the incorrect transmission path, is equipped against the incorrect operation of the transmission path. Thus, when the transmission path correctly operates, the isolator 122 increases the loss of the transmission path.
When the loss of the transmission path increases, the transmitter 110 raises the power in order to sustain the same antenna power as in the absence of the isolator 122. In so doing, the power consumption and the heat of the transmitter 110 rises and thus system throughput deteriorates.
Therefore, a need exists for an apparatus and a method for transmitting and receiving high-power RF signals in a TDD wireless communication system.